Suspension assembly for a bicycle

ABSTRACT

A trailing link, multi-link, suspension assembly for a bicycle having improved stability includes a first arm having a first arm fixed pivot and a first arm shock pivot. A shock link has a shock link fixed pivot and a shock link floating pivot. A shock absorber has a first shock mount and a second shock mount. A wheel carrier has a wheel carrier first pivot and a wheel carrier second pivot spaced apart from one another, and a wheel mount that is adapted to be connected to a wheel. A control link has a control link floating pivot and a control link fixed pivot, the control link floating pivot being pivotably connected to the wheel carrier second pivot, and the control link fixed pivot being pivotably connected to the first arm control pivot. A mechanical trail distance increases as the suspension assembly compresses relative to a fully extended state.

FIELD OF THE INVENTION

The disclosure is generally directed to bicycles, and more specificallydirected to bicycles having a suspension assembly that improvesstability.

BACKGROUND

Recently, telescopic front suspension forks have dominated suspensionsystems for bicycles. A telescopic fork includes sliding stantionsconnected in a steerable manner to a bicycle frame, and at the sametime, includes a telescoping mechanism for wheel displacement. Slidingstantions require very tight manufacturing tolerances, so expensiveround centerless ground stantions are almost always used in highperformance telescopic forks. Outer surfaces of the stantion typicallyslide against bushings to allow for compliance, and in many designs, theinner surfaces of the stantions slide against a damper or air springpiston to absorb shocks.

Front suspension for a bicycle is subject to large bending forces foreand aft and less significant lateral forces. The typically roundstantions in a telescopic fork must be sized to support the greatestloads encountered by the suspension during operation, which aretypically in the fore/aft direction. This requires the use of largesection or diameter stantions. The larger the stantions, the greater thearea of the supporting bushings and sliding surfaces. Because of thestacked layout, multiple redundant sliding surfaces must be used to sealin oil and air, as well as provide ample structural support.

Because telescopic forks have relatively large stantions, and relativelylarge siding surfaces and seals, large breakaway friction in the system(known as stiction) is generated by these components. Stiction resistscompression of the suspension in reaction to bumps, which is a drawbackin a suspension product where the goal is to react to road conditions,for example by deflecting in response to ground conditions, and/orabsorbing impact from bumps. Additionally, as the telescopic fork isloaded in the fore/aft direction (usually on impact or braking), thebushings bind, resulting in even greater stiction at the exact momentwhen a rider needs the most compliance.

The higher the fore/aft load on the telescopic fork, the less effectivethe telescopic fork is at absorbing bumps. Most modern telescopic forksfor bicycles and motorcycles exhibit around 130 Newtons of stiction attheir best, and thousands of Newtons of stiction when exposed tofore/aft loads.

Additionally, in the telescopic fork, mechanical trail is constrained bysteering axis (head tube) angle and fork offset, a term for theperpendicular distance between the wheel rotation axis and the steeringaxis. Another problem with telescopic fork architecture is that whenthey are installed, mechanical trail reduces as the suspension iscompressed, which reduces stability. When mechanical trail reduces, asthe suspension compresses, less torque is required to steer the frontwheel, causing a feeling of instability. This instability is a flaw inthe telescopic fork. However, because most riders of bicycles grew uponly riding telescopic forks, they only know this feeling and nothingelse. Thus, the inherent instability of a telescopic fork is theaccepted normal.

Another drawback of the telescopic fork is their lack of a leverageratio. Telescopic forks compress in a linear fashion in response tobumps. The wheel, spring, and damper all move together at the same ratebecause they are directly attached to each other. Because the forkcompresses linearly, and because the spring and damper are connecteddirectly to the wheel, the leverage ratio of wheel to damper and springtravel is a constant 1:1.

Yet another drawback of telescopic forks is that angle of attackstability and stiction increase and oppose one another. In other words,as angle of attack stability increases, stiction also increases, whichis undesirable. This problem is caused by the rearward angle of the forkstantions. The less steeply (slacker) the fork stantions are angled, thebetter the angle of attack is in relation to oncoming bumps. However,because the fork angle is largely governed by the steering axis (headtube) angle of the bicycle's frame the sliding stantions developincreased bushing load, and greater bending, resulting in increasedstiction when slacker fork angles are used.

A further drawback of telescopic forks is called front suspension dive.When a rider applies the front brake, deceleration begins and therider's weight transfers towards the front wheel, increasing load on thefork. As the telescopic front fork dives (or compresses) in response,the suspension stiffens, and traction reduces. This same load transferphenomenon happens in most automobiles as well, but there is adistinction with a telescopic fork.

The undesirable braking reaction in a bicycle telescopic fork is made upof two components, load transfer and braking squat. Load transfer,occurs when the rider's weight transfers forward during deceleration.That weight transfer causes an increased load on the front wheel, whichcompresses the front suspension. Braking squat is measured in the frontsuspension kinematics, and can have a positive, negative, or zero value.This value is independent of load transfer, and can have an additive orsubtractive effect to the amount of fork dive present during braking. Apositive value (known as pro-dive) forcibly compresses the frontsuspension when the brakes are applied, cumulative to the alreadypresent force from load transfer. A zero value has no braking reactionat all; the front suspension is free to respond naturally to the effectsof load transfer (for better or worse). A negative value (known asanti-dive) counteracts the front suspension's tendency to dive bybalancing out the force of load transfer with a counteracting force.

With a telescopic fork, the only possible braking squat reaction ispositive. Any time that the front brake is applied, the rider's weighttransfers forward, and additionally, the positive pro-dive braking squatreaction forcibly compresses the suspension. Effectively, this fools thefront suspension into compressing farther than needed, which reducesavailable travel for bumps, increases spring force, and reducestraction.

The inherent disadvantages of telescopic forks are not going away. Infact, as technology has improved in bicycling, the speeds and loads thatriders are putting into modern bicycles, cycles, motorcycles, andmountain cycles only make the challenges for the telescopic forkgreater.

SUMMARY

In accordance with one exemplary aspect, a bicycle suspension assemblyincludes a steering fork having a steering axis and a first arm. Thefirst arm has a first end and a second end, and includes a first armfixed pivot and a first arm shock pivot. The bicycle suspension assemblyalso includes a shock link having a shock link fixed pivot and a shocklink floating pivot spaced apart from one another. The shock link isoperatively connected to the first arm fixed pivot at the shock linkfixed pivot such that the shock link is rotatable, pivotable, orbendable about the shock link fixed pivot and the shock link fixed pivotremains in a fixed location relative to the first arm while the shocklink floating pivot is movable relative to the first arm. The bicyclesuspension assembly also includes a shock absorber having a first shockmount and a second shock mount, the first shock mount being operativelyconnected to the first arm shock pivot and the second shock mount beingoperatively connected to a shock connection pivot located between theshock link fixed pivot and the shock link floating pivot along a lengthof the shock link. The bicycle suspension assembly also includes a wheelcarrier having a wheel carrier first pivot and a wheel carrier secondpivot spaced apart from one another along a length of the wheel carrier.A wheel mount on the wheel carrier is adapted to be connected to a wheeland the wheel carrier first pivot is operatively connected to the shocklink floating pivot so that the wheel carrier second pivot is rotatable,pivotable, flexible or bendable about the wheel carrier first pivotrelative to the shock link floating pivot. The bicycle suspensionassembly also includes a control link having a control link floatingpivot and a control link fixed pivot. The control link floating pivot isoperatively connected to the wheel carrier second pivot, and the controllink fixed pivot is operatively connected to the first arm control pivotsuch that the control link floating pivot is rotatable, pivotable,flexible, or bendable about the control link fixed pivot, which remainsin a fixed location relative to the first arm control pivot. The fixedpivots and the floating pivots are arranged in a trailing configurationwhere each of the fixed pivots is forward of the corresponding floatingpivot in the forward direction of travel. A mechanical trail distance,which is a distance between a ground contact point of a wheel connectedto the wheel mount and the steering axis, increases as the suspensionassembly compresses relative to a fully extended state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a bicycle including a front wheel suspensionassembly constructed according to the teachings of the disclosure.

FIG. 1B is a side view of an alternate embodiment of a bicycle includinga front wheel suspension assembly constructed according to the teachingsof the disclosure, the bicycle of FIG. 1B including a rear wheelsuspension assembly.

FIG. 2 is a close up side view of the front wheel suspension assembly ofFIG. 1.

FIG. 3 is a side exploded view of the front wheel suspension assembly ofFIG. 2.

FIG. 4 is a side cut-away view of a shock absorber of the wheelsuspension assembly of FIG. 2.

FIG. 5 is a side schematic view of an alternate embodiment of a wheelsuspension assembly constructed according to the teachings of thedisclosure.

FIG. 6 A is a perspective view of a first embodiment of a pivot of thewheel suspension assembly of FIG. 2.

FIG. 6B is a side view of a second embodiment of a pivot of the wheelsuspension assembly of FIG. 2.

FIG. 6C is an exploded view of a third embodiment of a pivot of thewheel suspension assembly of FIG. 2.

FIG. 6D is a side view of a fourth embodiment of a pivot of the wheelsuspension assembly of FIG. 2.

FIG. 7 is a close up side view of the first arm of the front wheelsuspension assembly of FIG. 2 in a fully extended state.

FIG. 8 is a close up side view of the first arm of the front wheelassembly of FIG. 2 in a partially compressed intermediate state.

FIG. 9 is a close up side view of the first arm of the front wheelsuspension assembly of FIG. 2 in a further compressed state.

FIG. 10 is a close up side view of a first arm of an alternateembodiment of a front wheel suspension assembly in a fully extendedstate.

FIG. 11 is a close up side view of the first arm of the front wheelassembly of FIG. 10 in a partially compressed intermediate state.

FIG. 12 is a close up side view of the first arm of the front wheelsuspension assembly of FIG. 10 in a further compressed state.

DETAILED DESCRIPTION

The present invention is not to be limited in scope by the specificembodiments described below, which are intended as exemplaryillustrations of individual aspects of the invention. Functionallyequivalent methods and components fall within the scope of theinvention. Indeed, various modifications of the invention, in additionto those shown and described herein, will become apparent to thoseskilled in the art from the foregoing description. Such modificationsare intended to fall within the scope of the appended claims. Throughoutthis application, the singular includes the plural and the pluralincludes the singular, unless indicated otherwise. All citedpublications, patents, and patent applications are herein incorporatedby reference in their entirety.

As used herein, the terms “suspension assembly compression” and“suspension assembly displacement” are used interchangeably. The terms“suspension assembly compression” and “suspension assembly displacement”refer to movement and articulation of the suspension assembly duringcompression and extension of the shock absorber. More specifically,these terms refer to the component of movement, in a direction parallelto a steering axis, of the individual links and pivots of the suspensionassembly. Even more specifically, these terms refer to the movement ofthe wheel mount, on a wheel carrier of the suspension assembly, in adirection parallel to the steering axis. Furthermore, the suspensionassemblies described below are illustrated in fully extended, partiallycompressed, and further compressed states, which also refer tocorresponding relative displacements of the suspension assembly (e.g.,no displacement, partial displacement, and further displacement beyondthe partial displacement state). It should be understood that a riderwould only experience riding a cycle that is in a fully compressed statefor a very short period of time (on the order of milliseconds) as thesuspension assembly will naturally and substantially instantaneouslyequilibrates to a state with less compression than the fully compressedstate as the suspension assembly responds to changing riding conditions.

Turning now to FIG. 1A, a bicycle 10 includes a frame 12, a front wheel14 rotatably connected to a fork 30, which can be bifurcated or singlesided, and a rear wheel 16 rotatably connected to the frame 12. The rearwheel 16 is drivable by a drive mechanism, such as a chain 18 connectedto a wheel sprocket 20 and to a chainring 22, so that driving force maybe imparted to the rear wheel 16. The fork 30, allows the front wheel 14to deflect in response to ground conditions as a rider rides the bicycleand to improve handling and control during riding. To improve handlingcharacteristics, the fork 30 and the front wheel 14 may be operativelyconnected to a suspension assembly or linkage 46. The frame 12 mayoptionally include a rear wheel suspension assembly (not shown in FIG.1A), which may allow the rear wheel 16 to deflect in response to groundconditions as a rider rides the bicycle and to improve handling andcontrol during riding.

Turning now to FIG. 1B, a bicycle 10 includes a frame 12, a front wheel14 rotatably connected to a fork 30, which can be bifurcated or singlesided, and a rear wheel 16 rotatably connected to the frame 12. The fork30 and the front wheel 14 may be operatively connected to a suspensionassembly or linkage 46. The rear wheel 16 is drivable by a drivemechanism, such as a chain 18 connected to a wheel sprocket 20 and to achainring 22, so that driving force may be imparted to the rear wheel16. The fork 30, allows the front wheel 14 to deflect in response toground conditions as a rider rides the bicycle and to improve handlingand control during riding. The frame 12 may optionally include a rearwheel suspension assembly 24, which may allow the rear wheel 16 todeflect in response to ground conditions as a rider rides the bicycleand to improve handling and control during riding.

As illustrated in FIGS. 2-4, the fork 30 includes a first arm 32operatively connected to a steering shaft 34. The steering shaft 34includes a steering axis S that is formed by a central axis of thesteering shaft 34. The first arm 32 has a first end and 36 a second end38, the first arm 32 including a first arm fixed pivot 40 and a firstarm shock pivot 42. The first arm shock pivot 42 operably connects asuspension device, such as a shock absorber 44 to the first arm 32. Forexample, the first arm shock pivot 42 allows relative motion, in thiscase rotation, between the shock absorber 44 and the first arm 32. Inother embodiments, other types of relative motion, such as flexure ortranslation, between the shock absorber 44 and the first arm 32 may beemployed. The first arm fixed pivot 40 pivotably connects one element ofthe linkage 46, as discussed further below, to the first arm 32.

A shock link 50 is pivotably connected to the first arm fixed pivot 40.The shock link 50 includes a shock link fixed pivot 52 and a shock linkfloating pivot 54 spaced apart from one another along a length of theshock link 50. The shock link 50 is pivotably connected to the first armfixed pivot 40 at the shock link fixed pivot 52 such that the shock link50 is rotatable about the shock link fixed pivot 52 and the shock linkfixed pivot 52 remains in a fixed location relative to the first arm 32,while the shock link floating pivot 54 is movable relative to the firstarm 32.

A pivot, as used herein, includes any connection structure that may beused to operatively connect one element to another element, and thatallows relative movement between the connected components. An operativeconnection may allow for one component to move in relation to anotherwhile constraining movement in one or more degrees of freedom. Forexample, the one degree of freedom may be pivoting about an axis. In oneembodiment, a pivot may be formed from a journal or through hole in onecomponent and an axle in another component. In other examples, pivotsmay include ball and socket joints. Yet other examples of pivotsinclude, but are not limited to singular embodiments and combinationsof, compliant mounts, sandwich style mounts, post mounts, bushings,bearings, ball bearings, plain bearings, flexible couplings, flexurepivots, journals, holes, pins, bolts, and other fasteners. Also, as usedherein, a fixed pivot is defined as a pivotable structure that does notchange position relative the first arm 32. As used herein, a floatingpivot is defined as a pivot that is movable (or changes position)relative to another element, and in this case, is movable relative tofirst arm 32.

The suspension assembly or linkage 46 is configured in a trailingorientation. A trailing orientation is defined herein as a linkage thatincludes a fixed pivot that is forward of the corresponding floatingpivot when the bicycle is traveling in the forward direction of travelas represented by arrow A in FIGS. A and 1B. In other words, thefloating pivot trails the fixed pivot when the bicycle is traveling inthe forward direction of travel. For example, in the illustratedembodiment, the shock link fixed pivot 52 is forward of the shock linkfloating pivot 54. The disclosed suspension assembly or linkage 46 isalso characterized as a multi-link suspension assembly. A multi-linksuspension assembly is defined herein as a suspension assembly having aplurality of interconnected links in which any part of the front wheel14 is directly connected to a link in the plurality of interconnectedlinks that is not directly connected to the fork 30.

The shock absorber 44 includes a first shock mount 56 and a second shockmount 58, the first shock mount 56 being pivotably connected to thefirst arm shock pivot 42, the second shock mount 58 being pivotablyconnected to a shock connection pivot 60 located between the shock linkfixed pivot 52 and the shock link floating pivot 54 along a length ofthe shock link 50.

A wheel carrier 62 includes a wheel carrier first pivot 64 and a wheelcarrier second pivot 66 spaced apart from one another along a length ofthe wheel carrier 62. Both the wheel carrier first pivot 64 and thewheel carrier second pivot 66 are floating pivots, as they both moverelative to the first arm 32. A wheel mount 68 is adapted to beconnected to a center of a wheel, for example the front wheel 14. In thedisclosed embodiment, a center of the front wheel 14 is rotatablyconnected to the wheel mount 68. The wheel carrier first pivot 64 ispivotably connected to the shock link floating pivot 54 so that thewheel carrier second pivot 66 is pivotable about the wheel carrier firstpivot 64 relative to the shock link floating pivot 54.

A control link 70 includes a control link floating pivot 72 and acontrol link fixed pivot 74. The control link floating pivot 72 ispivotably connected to the wheel carrier second pivot 66, and thecontrol link fixed pivot 74 is pivotably connected to a first armcontrol pivot 76 located on the first arm 32 such that the control linkfloating pivot 72 is pivotable about the control link fixed pivot 74,which remains in a fixed location relative to the first arm controlpivot 76.

In some embodiments, the shock connection pivot 60 is closer to theshock link fixed pivot 52 than to the shock link floating pivot 54, asillustrated in FIGS. 2 and 3. As a function of suspension compressionand link movement, a perpendicular distance D between a central axis Iof an inshaft 80 of the shock absorber 44 and a center of the shock linkfixed pivot 52 varies as the shock absorber 44 is compressed andextended, as the shock absorber pivots about the first shock mount 56.This pivoting and varying of the perpendicular distance D allows theleverage ratio and motion ratio to vary as the shock absorber 44compresses and extends. As a function of suspension compression and linkmovement, a mechanical trail distance T varies as the shock absorber 44compresses and extends. The mechanical trail distance T is defined asthe perpendicular distance between the steering axis S and the contactpoint 82 of the front wheel 14 with the ground 84. More specifically, asthe suspension compresses, beginning at a state of full extension, themechanical trail distance T increases, thus increasing stability duringcompression. Compression is usually experienced during braking,cornering, and shock absorbing, all of which benefit from increasedstability that results from the mechanical trail distance increase.

Mechanical trail (or “trail”, or “caster”) is an important metricrelating to handling characteristics of bicycles. Mechanical trail is aconfiguration in which the wheel is rotatably attached to a fork, whichhas a steering axis that is offset from the contact point of the wheelwith the ground. When the steering axis is forward of the contact point,as in the case of a shopping cart, this configuration allows the casterwheel to follow the direction of cart travel. If the contact point movesforward of the steering axis (for example when reversing direction of ashopping cart), the directional control becomes unstable and the wheelspins around to the original position in which the contact point trailsthe steering axis. The friction between the ground and the wheel causesa self-righting torque that tends to force the wheel to trail thesteering axis. The greater the distance between the contact point andperpendicular to the steering axis, the more torque is generated, andthe greater the stability of the system. Similarly, the longer thedistance between the wheel contact point and perpendicular to thesteering axis, the more torque is generated, and the greater thestability of the system. Conversely, the shorter the distance betweenthe wheel contact point and perpendicular to the steering axis, the lesstorque is generated, and the lower the stability of the system.

This caster effect is an important design characteristic in bicycles.Generally, the caster effect describes the bicycle rider's perception ofstability resulting from the mechanical trail distance described above.If the wheel gets out of line, a self-aligning torque automaticallycauses the wheel to follow the steering axis again due to theorientation of the wheel ground contact point being behind the steeringaxis of the fork. As the contact point of the wheel with the ground ismoved further behind the steering axis, self aligning torque increases.This increase in stability is referred to herein as the caster effect.

In the disclosed wheel suspension assembly, when the suspension is at astate of full extension, the steering axis of the fork 30 projects aheadof the contact point 82. As the suspension assembly moves towards astate of full compression, the steering axis S projects farther ahead ofthe contact point 82, which results in the stability increasing. Thisincreased stability stands in contrast to known telescopic forkbicycles, which experience reduced trail and thus reduced stabilityduring compression.

Leverage ratios or motion ratios are important metrics relating toperformance characteristics of some suspensions. In certain embodiments,a shock absorber can be compressed at a constant or variable rate as thesuspension moves at a constant rate towards a state of full compression.As a wheel is compressed, incremental suspension compression distancemeasurements are taken. Incremental suspension compression distance ismeasured from the center of the wheel at the wheel rotation axis andparallel with the steering axis, starting from a state of fullsuspension extension, and moving towards a state of full suspensioncompression. These incremental measurements are called the incrementalsuspension compression distance. A shock absorber length can be changedby wheel link, and/or brake link, and/or control link movements as thesuspension compresses. At each incremental suspension compressiondistance measurement, a shock absorber length measurement is taken. Therelationship between incremental suspension compression distance changeand shock absorber length change for correlating measurements of thesuspension's compression is called leverage ratio or motion ratio.Leverage ratio and motion ratio are effectively equivalent butmathematically different methods of quantifying the effects of variablesuspension compression distance versus shock compression distance.Overall leverage ratio is the average leverage ratio across the entirerange of compression. Overall leverage ratio can be calculated bydividing the total suspension compression distance by the total shockabsorber compression distance. Overall motion ratio is the averagemotion ratio across the entire range of compression. Overall motionratio can be calculated by dividing the total shock absorber compressiondistance by the total suspension compression distance.

Generally, a suspended wheel has a compressible wheel suspension traveldistance that features a beginning travel state where the suspension iscompletely uncompressed to a state where no further suspension extensioncan take place, and an end travel state where a suspension is completelycompressed to a state where no further suspension compression can takeplace. At the beginning of the wheel suspension travel distance, whenthe suspension is in a completely uncompressed state, the shock absorberis in a state of least compression, and the suspension is easilycompressed. As the suspended wheel moves compressively, force at thewheel changes in relation to shock absorber force multiplied by aleverage ratio. A leverage ratio is defined as the ratio of compressivewheel travel change divided by shock absorber measured length changeover an identical and correlating given wheel travel distance. A motionratio is defined as the ratio of shock absorber measured length changedivided by compressive wheel travel change over an identical andcorrelating given wheel travel distance.

In known telescopic forks no leverage ratio exists and, the leverageratio is always equivalent to 1:1 due to the direct coupling of thewheel to the shock absorber.

A leverage ratio curve is a graphed quantifiable representation ofleverage ratio versus wheel compression distance or percentage of fullcompression distance. Wheel compression distance, suspensioncompression, or wheel travel is measured from the center of the wheel atthe wheel rotation axis and parallel with the steering axis, with theinitial 0 percent measurement taken at full suspension extension withthe vehicle unladen. As a suspension is compressed from a state of fullextension to a state of full compression at a constant rate,measurements of shock absorber length are taken as the shortest distancebetween a first shock pivot and a second shock pivot at equal incrementsof suspension compression. When graphed as a curve on a Cartesian graph,leverage ratio is shown on the Y axis escalating from the x axis in apositive direction, and vertical wheel travel is shown on the X axisescalating from the Y axis in a positive direction.

A motion ratio curve is a graphed quantifiable representation of motionratio versus wheel compression distance or percentage of fullcompression distance. Wheel compression distance, suspensioncompression, or wheel travel is measured from the center of the wheel atthe wheel rotation axis and parallel with the steering axis, with theinitial 0 percent measurement taken at full suspension extension withthe vehicle unladen. As a suspension is compressed from a state of fullextension to a state of full compression, measurements of shock absorberlength are taken as the shortest distance between a first shock pivotand a second shock pivot at equal increments of suspension compression.When graphed as a curve on a Cartesian graph, motion ratio is shown onthe Y axis escalating from the x axis in a positive direction, andvertical wheel travel is shown on the X axis escalating from the Y axisin a positive direction.

In certain embodiments, a leverage ratio or motion ratio curve can bebroken down into three equal parts in relation to wheel compressiondistance or vertical wheel travel, a beginning ⅓ (third), a middle ⅓,and an end ⅓. In certain embodiments, a beginning ⅓ can comprise apositive slope, zero slope, and or a negative slope. In certainembodiments, a middle ⅓ can comprise a positive slope, zero slope, andor a negative slope. In certain embodiments, an end ⅓ can comprise apositive slope, zero slope, and or a negative slope. Certain preferredleverage ratio embodiments can comprise a beginning ⅓ with a positiveslope, a middle ⅓ with a less positive slope, and an end ⅓ with a morepositive slope. Certain preferred leverage ratio embodiments cancomprise a beginning ⅓ with a negative slope, a middle ⅓ with negativeand zero slope, and an end ⅓ with a positive slope. Certain preferredleverage ratio embodiments can comprise a beginning ⅓ with a positiveand negative slope, a middle ⅓ with negative and zero slope, and an end⅓ with a positive slope. Certain preferred leverage ratio embodimentscan comprise a beginning ⅓ with a positive and negative slope, a middle⅓ with negative and zero slope, and an end ⅓ with a more negative slope.Certain preferred motion ratio embodiments can comprise a beginning ⅓with a negative slope, a middle ⅓ with a less negative slope, and an end⅓ with a more negative slope. Certain preferred motion ratio embodimentscan comprise a beginning ⅓ with a positive slope, a middle ⅓ withpositive and zero slope, and an end ⅓ with a negative slope. Certainpreferred motion ratio embodiments can comprise a beginning ⅓ with anegative and positive slope, a middle ⅓ with positive and zero slope,and an end ⅓ with a negative slope. Certain preferred motion ratioembodiments can comprise a beginning ⅓ with a negative and positiveslope, a middle ⅓ with positive and zero slope, and an end ⅓ with a morepositive slope.

In contrast to telescopic suspensions, the disclosed wheel suspensionassembly provides a greater than 1:1 overall leverage ratio between theshock absorber 44 and the shock link 50, due to the indirect coupling(through the linkage 46) of the wheel 14 and the shock absorber 44. Incontrast to telescopic suspensions, the disclosed wheel suspensionassembly provides a less than 1:1 overall motion ratio between the shockabsorber 44 and the shock link 50, due to the indirect coupling (throughthe linkage 46) of the wheel 14 and the shock absorber 44. Additionally,because of the movement arcs of the various linkage elements, at anygiven point during compression, instantaneous leverage ratio and motionratio can vary non-linearly.

The central axis I of the inshaft 80 of the shock absorber 44 isarranged to form an angle B of between 0° and 20° relative to a centralaxis F of the first arm 32, the central axis F of the first arm 32 beingdefined by a line formed between the first arm shock pivot 42 and thefirst arm fixed pivot 40. In other embodiments, the central axis I ofthe inshaft 80 of the shock absorber 44 forms an angle with the centralaxis F of the first arm 32 of between 0° and 15°. In other embodiments,the central axis I of the inshaft 80 of the shock absorber 44 forms anangle with the central axis F of the first arm 32 of between 0° and 30°.The angle B may vary within these ranges during compression andextension.

In some embodiments, the first arm 32 includes a hollow portion 86 andthe shock absorber 44 is located at least partially within the hollowportion 86 of the first arm 32.

The shock link fixed pivot 52 is offset forward of the central axis I ofthe inshaft 80 of the shock absorber 44. In other words, the centralaxis I of the inshaft 80 of the shock absorber 44 is positioned betweenthe shock link fixed pivot 52 and the shock link floating pivot 54 in aplane defined by the central axis I of the inshaft 80, the shock linkfixed pivot 52 and the shock link floating pivot 54 (i.e., the planedefined by the view of FIG. 2).

A line between the wheel carrier first pivot 64 and the wheel carriersecond pivot 66 defines a wheel carrier axis WC, and the wheel mount 68is offset from the wheel carrier axis WC in a plane defined by the wheelcarrier axis WC and the wheel mount 68 (i.e., the plane defined by theview of FIG. 3). In some embodiments, the wheel mount 68 is offset fromthe wheel carrier axis WC towards the first arm 32, for example theembodiment illustrated in FIGS. 2 and 3. In other embodiments, the wheelmount 68 may be offset from the wheel carrier axis WC away from thefirst arm 32.

In the embodiment of FIGS. 2 and 3, the wheel mount 68 is located aft ofthe shock link fixed pivot 52, such that the central axis I of theinshaft 80 of the shock absorber 44 is located between the wheel mount68 and the shock link fixed pivot 52 in a plane defined by the centralaxis I of the inshaft 80 of the shock absorber 44, the wheel mount 68and the shock link fixed pivot 52 (i.e., the plane defined by the viewof FIG. 2).

Turning now to FIG. 4, in some embodiments, the shock absorber 44includes a shock body, in some embodiments comprising a spring anddamper87. The shock absorber may further include the inshaft 80 thatextends from the shock body 87. The second shock mount 58 is formed atone end of the inshaft 80, and the inshaft 80 is pivotably connected tothe shock connection pivot 60 by the second shock mount 58 such that theinshaft 80 is compressible and extendable relative to the shock body 87as the shock link 50 pivots about the shock link fixed pivot 52.

FIG. 5 illustrates the wheel suspension assembly in engineering symbolsthat distinguish a spring 47 and dashpot 49 of the shock absorber 44.

Returning now to FIGS. 2-4, the control link 70 is pivotably mounted tothe first arm 32 at the first arm control pivot 76 that is locatedbetween the first arm fixed pivot 40 and the first arm shock pivot 42,along a length of the first arm 32.

Turning now to FIGS. 6A-6D, several embodiments of structures areillustrated that may be used as the pivots (fixed and/or floating)described herein.

FIG. 6A illustrates a cardan pivot 100. The cardan pivot includes afirst member 101 and a second member 102 that are pivotably connected toone another by yoke 105 which comprises a first pin 103 and a second pin104. As a result, the first member 101 and the second member 102 maymove relative to one another about an axis of the first pin 103 and/orabout an axis of the second pin 104.

FIG. 6B illustrates a flexure pivot 200. The flexure pivot 200 includesa flexible portion 203 disposed between a first member 201 and a secondmember 202. In the illustrated embodiment, the first member 201, thesecond member 202, and the flexible portion 203 may be integrallyformed. In other embodiments, the first member 201, the second member202, and the flexible portion 203 may be separate elements that areconnected to one another. In any event, the flexible portion 203 allowsrelative motion between the first member 201 and the second member 202about the flexible portion 203. The flexible portion 203 is moreflexible than the members 201 and 202, permitting localized flexure atthe flexible portion 203. In the illustrated embodiment, the flexibleportion 203 is formed by a thinner portion of the overall structure. Theflexible portion 203 is thinned sufficiently to allow flexibility in theoverall structure. In certain embodiments, the flexible portion 203 isshorter than 100 mm. In certain embodiments, the flexible portion 203 isshorter than 70 mm. In certain embodiments, the flexible portion 203 isshorter than 50 mm. In certain embodiments, the flexible portion 203 isshorter than 40 mm. In certain preferred embodiments, the flexibleportion 203 is shorter than 30 mm. In certain other preferredembodiments, the flexible portion 203 is shorter than 25 mm.

FIG. 6C illustrates a bar pin pivot 300. The bar pin pivot includes afirst bar arm 301 and a second bar arm 302 that are rotatably connectedto a central hub 303. The central hub 303 allows the first bar arm 301and the second bar arm 302 to rotate around a common axis.

FIG. 6D illustrates a post mount pivot 400. The post mount pivot 400includes a mounting stem 401 that extends from a first shock member 402.The mounting stem 401 is connected to a structure 407 by a nut 404, oneor more retainers 405, and one or more grommets 406. The first shockmember 402 is allowed relative movement by displacement of the grommets406, which allows the mounting stem 401 to move relative to a structure407 in at least one degree of freedom.

Turning to FIGS. 7-12, generally, as the suspension assembly 46initially compresses (e.g., one or more links in the suspension assemblyhas a component of movement in a direction 510 that is substantiallyparallel to the steering axis S), a mechanical trail distance Tinitially increases due to the angular change in the steering axis S,which projects a bottom of the steering axis forward, relative to thewheel contact point 82 with the ground 84. This increase in mechanicaltrail distance T also increases the caster effect by creating a largermoment arm, between the steering axis 82 and the wheel contact point 82,to correct off-center deflections of the wheel 14. As a result, thewheel 14 becomes more statically and dynamically stable as thesuspension assembly 46 compresses and the mechanical trail distance Tincreases. For example, for each embodiment disclosed herein, whensuspension assembly compression is initiated (relative to anuncompressed state), mechanical trail distance T increases. Mechanicaltrail distance T may increase, for example continuously increase, from aminimum value in the uncompressed state of the suspension assembly to amaximum value in the fully compressed state of the suspension assembly.In other embodiments, mechanical trail distance T may increase initiallyfrom the uncompressed state of the suspension assembly to a maximumvalue at a partially compressed intermediate state of the suspensionassembly, and then mechanical trail distance T may decrease from themaximum value as the suspension assembly 46 continues compression fromthe partially compressed intermediate state to the fully compressedstate.

When the disclosed suspension assembly 46 is at a fully extended state(e.g., uncompressed), as illustrated in FIG. 7, for example, thesteering axis S projects ahead of the contact point 82, where the wheel14 contacts the ground 84. In various states of compression betweenuncompressed and fully compressed, suspension assembly compression canbe measured as a component of linear distance that the wheel mount 68moves in a travel direction 510 aligned with and parallel to thesteering axis S.

As the suspension assembly 46 initially begins to compress, thesuspension assembly 46 moves through a partially compressed intermediatestate, as illustrated in FIG. 8. In the partially compressedintermediate state illustrated in FIG. 8, the steering axis S projectsfarther ahead of the contact point 82 than in the fully extended stateof FIG. 7, which results in a decrease of an offset distance 515 of thewheel mount and a corresponding increase in the mechanical traildistance T. In the embodiment of FIGS. 7-9, the offset distance 515,which is defined as the perpendicular distance between the steering axisS and a center of the wheel mount 68 of the front wheel 14, decreases asthe suspension assembly 46 compresses. The offset distance 515 generallydecreases during suspension assembly compression because the wheel mount68 moves in the aft direction, to the left in FIGS. 9-11. In otherembodiments, for example in the embodiments of FIGS. 10-12, as thesuspension assembly 46 compresses, beginning at a state of fullextension, the offset distance 515 can increase or decrease (e.g., moveforward or aft (right or left respectively in FIGS. 12-14)), duringsuspension compression, depending on variables including wheel 14diameter, steering angle 520, and initial mechanical trail distance T.

The mechanical trail distance T is larger in the partially compressedintermediate state of FIG. 8 than in the fully extended state of FIG. 7.This increase in mechanical trail distance T results in increasedstability, as described above. This increased mechanical trail distanceT, and corresponding increase in stability, is the opposite result ofwhat happens when telescopic fork suspension assemblies compress, whichis a reduced mechanical trail distance and thus, a reduction instability. Increasing mechanical trail distance as the suspensionassembly compresses is a significant performance advantage over existingsuspension assemblies.

As stated above, the increase in mechanical trail distance T as thesuspension assembly 46 compresses advantageously increases wheelstability due to the increased caster effect. Compression is usuallyexperienced during challenging riding conditions, such as braking,cornering, and shock absorbing, all of which benefit from theadvantageously increased stability that results from the mechanicaltrail distance increase observed in the disclosed front wheel suspensionassemblies.

As the suspension assembly 46 moves towards the further compressedstate, for example as illustrated in FIG. 9, the steering axis Sprojects even farther ahead of the contact point 82, which results in afurther decrease of a wheel carrier displacement distance 515 and acorresponding further increase in the mechanical trail distance T. Themechanical trail distance T is larger in the further compressed state ofFIG. 9 than in the fully extended state of FIG. 7 or than in thepartially compressed intermediate state of FIG. 8. This increase inmechanical trail distance T results in further increased stability. Inthe embodiment of FIGS. 7-9, increased mechanical trail distance T, andthus increased stability, occur when the suspension assembly is in thefurther compressed state (FIG. 9). In some embodiments, the mechanicaltrail distance T may decrease between the further compressed state (FIG.11) and a fully compressed state (not shown). In yet other embodiments,the mechanical trail distance T may continue to increase from thefurther compressed state (FIG. 11) to the fully compressed state (notshown).

As a function of suspension compression and link movement, themechanical trail distance T, and the offset distance 515, vary as thesuspension assembly compresses and extends. In some embodiments, themechanical trail distance T may increase, for example continuouslyincrease, from full extension to full compression. In some embodiments,the increase in mechanical trail distance T may occur at a non constant(e.g., increasing or decreasing) rate.

In yet other embodiments (e.g., the embodiment illustrated in FIGS.10-12), the mechanical trail distance T may increase initially as thesuspension assembly compresses to the partially compressed intermediatestate (FIG. 11), which results in an increased mechanical trail distanceT. The partially compressed intermediate state (FIG. 11) is a state ofsuspension assembly compression between the fully extended state (FIG.10) and the further compressed state (FIG. 12).

In the embodiment of FIGS. 10-12, the wheel carrier 62 includes a wheelmount 68 that is located close to an axis drawn between the wheelcarrier floating pivots 64, 66. This location for the wheel mount 68results in the wheel mount 68 crossing the steering axis duringcompression of the suspension assembly 46.

More specifically, in the fully extended state of FIG. 10, the wheelmount 68 is located on a first side (to the front or right side in FIG.10) of the steering axis S and the offset distance 515 is positive (tothe front or right of the steering axis S). The mechanical traildistance T is correspondingly at a minimum value. As the suspensionassembly 46 compresses to the partially compressed intermediate state(FIG. 11), the wheel mount 68 moves aft (left in FIG. 11) and crossesthe steering axis S to a second side (to the aft or left side in FIG.11) and the offset distance 515 is reduced to the point that it becomesnegative (to the aft or left of the steering axis S). This movementresults in an increase in the mechanical trail distance T to a greatervalue than the mechanical trail distance T of the fully extended state(FIG. 10). As the suspension assembly 46 continues to compress to thefurther compressed state (FIG. 12), the wheel mount 68 again movesforward and crosses the steering axis S back to the first side andbecomes positive again (to the front or right of the steering axis S),which results in a decrease in mechanical trail distance T relative tothe partially compressed intermediate state of FIG. 11. However, themechanical trail distance T at the further compressed state (FIG. 12) isgreater than the mechanical trail distance T in the fully extended state(FIG. 10), but less than the mechanical trail distance in the partiallycompressed intermediate state (FIG. 11).

Generally, as the suspension assemblies 46 described herein compress,the links in the suspension assembly 46 articulate, varying the offsetdistance 515, as described above. The offset distance 515 changes tocounteract a concurrent steering angle 520 change such that themechanical trail distance T is varied as described above.

Herein, particularly with regard to FIGS. 7-12, the disclosed frontwheel suspension assembly is shown and described in various states ofcompression or displacement. It should be understood that the frontwheel displacement of the suspension assemblies described herein doesnot include any effects of a rear wheel suspension assembly. A rearsuspension assembly when present will alter the various relative changesof the offset 515, mechanical trail distance T, the steering angle 520as shown and described during compression of the suspension assembly.Thus, the displacement of the suspension assemblies is shown anddescribed herein as excluding any effects of a rear wheel suspensionassembly. For example, where a rear wheel suspension assembly isincluded on a cycle in combination with a suspension assembly asdisclosed herein, the cycle can be described as being capable of frontwheel suspension assembly displacement as described herein and/or asdemonstrating the front wheel suspension assembly compressioncharacteristics described herein when the rear suspension assemblycharacteristics and effects are subtracted from the overall performanceof the cycle.

The disclosed wheel suspension assemblies can be designed to be lighterin weight, lower in friction, more compliant, safer, and perform betterthan traditional wheel suspension assemblies.

The disclosed wheel assemblies also reduce stiction and increasestability during braking, cornering, and shock absorption, when comparedto traditional wheel suspension assemblies.

The disclosed wheel suspension assemblies are particularly well suitedto E-bikes. E-bikes are heavier and faster than typical mountain bikes.They are usually piloted by less skilled and less fit riders, andrequire a stronger front suspension to handle normal riding conditions.E-bikes are difficult to build, requiring the challenging integration ofmotors and batteries into frame designs. In many cases, the electricparts are large and unsightly.

E-bikes are typically cost prohibitive to build as well, requiringspecial fittings to adapt motors and batteries. To integrate onecenter-drive motor, the additional cost to the manufacturer is aboutdouble the price of a common bicycle frame. That cost is multiplied andpassed onto the consumer.

The beneficial caster effect described above with respect to thedisclosed wheel suspension assemblies is an important improvement overtraditional wheel suspension assemblies and reduces some of thedrawbacks of E-bikes.

Additionally, because the disclosed wheel suspension assemblies are notconstrained by round stantions, the oval fork legs balance fore-aft andside to side compliance for ultimate traction. Combining superiorchassis stiffness while eliminating stiction gives the disclosed wheelsuspension assemblies a performance advantage over traditional wheelsuspension assemblies.

While a two-wheeled bicycle is disclosed, the disclosed wheel assembliesare equally applicable to any cycle, such as bicycle, motorcycle,unicycle, or tricycle vehicles.

Furthermore, the disclosed wheel suspension assemblies are easilyretrofittable to traditional bicycles.

What is claimed:
 1. A bicycle comprising: a frame; a rear wheelrotatably mounted to the frame; a steering fork operatively connected tothe frame, the steering fork being operably connected to a first arm,the steering fork rotating about a steering axis relative to the frame,the first arm being angled relative to the steering axis, the first armhaving a first end and a second end, and the first arm including a firstarm fixed pivot, a first arm shock pivot and a first arm control pivot;a shock link, the shock link having a shock link fixed pivot and a shocklink floating pivot spaced apart from one another, the shock link beingpivotably connected to the first arm fixed pivot at the shock link fixedpivot such that the shock link is rotatable about the shock link fixedpivot and the shock link fixed pivot remains in a fixed locationrelative to the first arm while the shock link floating pivot is movablerelative to the first arm; a shock absorber having a first shock mountand a second shock mount, the first shock mount being connected to thefirst arm shock pivot, the second shock mount being pivotably connectedto a shock connection pivot located between the shock link fixed pivotand the shock link floating pivot along a length of the shock link; awheel carrier, the wheel carrier having a wheel carrier first pivot anda wheel carrier second pivot spaced apart from one another along alength of the wheel carrier, and a wheel mount, the wheel carrier firstpivot being pivotably connected to the shock link floating pivot so thatthe wheel carrier second pivot is rotatable about the wheel carrierfirst pivot relative to the shock link floating pivot; a control link,the control link including a control link floating pivot and a controllink fixed pivot, the control link floating pivot being pivotablyconnected to the wheel carrier second pivot, and the control link fixedpivot being pivotably connected to the first arm control pivot such thatthe control link floating pivot is rotatable about the control linkfixed pivot, which remains in a fixed location relative to the first armcontrol pivot; and a front wheel rotatably attached to the wheel carrierat the wheel mount, wherein the fixed pivots and the floating pivots arearranged in a trailing configuration where each of the fixed pivots isforward of the corresponding floating pivot in the forward direction oftravel of the bicycle, and wherein, a mechanical trail distance, whichis a distance between a ground contact point of a wheel connected to thewheel mount and the steering axis, increases as the suspension assemblycompresses relative to a fully extended state.
 2. The bicycle of claim1, wherein the shock connection pivot is closer to the shock link fixedpivot than to the shock link floating pivot, and a perpendiculardistance between a longitudinal axis of an inshaft of the shock absorberand the shock link fixed pivot varies as the shock absorber iscompressed and extended.
 3. The bicycle of claim 2, wherein the shockabsorber and the shock link generate a greater than 1:1 overall leverageratio.
 4. The bicycle of claim 3, wherein an instantaneous leverageratio varies non-linearly as the shock absorber is compressed andextended.
 5. The bicycle of claim 1, wherein a central axis of aninshaft of the shock absorber is arranged to form an angle of between 0°and 20° relative to a central axis of the first arm, the central axis ofthe first arm being defined by a line between the first arm shock pivotand the first arm fixed pivot.
 6. The bicycle of claim 1, wherein theshock absorber is located at least partially within a hollow portion ofthe first arm.
 7. The bicycle of claim 1, wherein the shock link fixedpivot is offset forward of a central axis of an inshaft of the shockabsorber, the central axis of the inshaft of the shock absorber beingpositioned between the shock link fixed pivot and the shock linkfloating pivot in a plane defined by the central axis of the inshaft,the shock link fixed pivot and the shock link floating pivot.
 8. Thebicycle of claim 1, wherein a line between the wheel carrier first pivotand the wheel carrier second pivot define a wheel carrier axis, and thewheel mount is offset from the wheel carrier axis in a plane defined bythe wheel carrier axis and the wheel mount.
 9. The bicycle of claim 8,wherein the wheel mount is offset from the wheel carrier axis away fromthe steering axis.
 10. The bicycle of claim 8, wherein the wheel mountis offset from the wheel carrier axis towards the steering axis.
 11. Thebicycle of claim 8, wherein the wheel mount is located aft of the shocklink fixed pivot, such that a central axis of an inshaft of the shockabsorber is located between the wheel mount and the shock link fixedpivot in a plane defined by the inshaft of the shock absorber, the wheelmount and the shock link fixed pivot.
 12. The bicycle of claim 1,wherein the shock absorber includes a shock body.
 13. The bicycle ofclaim 12, wherein the shock absorber further includes an inshaft thatextends from the shock body and out of the first arm, the second shockmount being formed at one end of the inshaft, and the inshaft ispivotably connected to the shock connection pivot by the second shockmount such that the inshaft is compressible relative and extendablerelative to the shock body as the shock link pivots about the fixedpivot.
 14. The bicycle of claim 13, wherein the control link ispivotably connected to the first arm at a second arm pivot that islocated between the first arm fixed pivot and the first arm shock pivot.